Background <p>Thoracoabdominal hernias (TH), encompassing abdominal wall hernias such as flank hernias and diaphragmatic hernias, are rare conditions with poorly defined epidemiology and no standardized surgical strategy. Repair is technically challenging because it requires reconstruction across distinct anatomical structures, including the diaphragm, ribs, and abdominal wall. Optimal repair methods remain controversial.</p> Case presentation <p>A 70-year-old man with a history of descending aortic aneurysm repair presented with a progressive left flank bulge. Computed tomography revealed a large flank hernia accompanied by diaphragmatic deformation, suggesting a concomitant diaphragmatic hernia. Surgical repair was performed via a previous thoracoabdominal incision. Intraoperatively, dehiscence of the diaphragm from the rib cage was identified. The diaphragmatic defect was primarily closed and reinforced by anchoring the diaphragm to the ribs using full-thickness sutures. Subsequently, the flank hernia was repaired using a modified extraperitoneal mesh repair with wide dissection and cranial fixation of the mesh to the ribs, followed by additional onlay mesh reinforcement. The postoperative course was uneventful, and no recurrence or chronic pain was observed during follow-up.</p> Conclusion <p>Combined reconstruction of the diaphragm and abdominal wall using rib-anchored diaphragmatic repair and extraperitoneal mesh placement may be an effective option for complex thoracoabdominal hernias. This approach enables secure fixation and broad mesh overlap while minimizing postoperative bulging. Further studies are needed to validate its safety, durability, and long-term outcomes.</p>